We plan to explore the use of GVS on the severity of attention span deficits and motor training delivered using a spring-based robot. We intend to carry out the study in a small cohort of traumatic brain injury (TBI) survivors (20 subjects). Subjects with attention span deficits but no significant motor impairments will solely undergo a cognitive test of attention with/without GVS. Subjects with both attention span deficits and significant motor impairments will undergo a cognitive test of attention and robot-assisted upper-limb rehabilitation with/without GVS.